Hi,
I've been having the same problem which appeared to start on the 19th May 2022 (in case anyone looks at this at a later date). I've located the issue to the way the start script determines the username. The following is the line in the start.sh script which can be found in the Resilio installation directory (for me it's /mnt/HD/HD_a2/Nas_Prog/ResilioSync:
USERNAME=$(grep '/home/admin' /etc/passwd | cut -d ':' -f1)
The problem appears to be that the update has removed the admin's home directory i.e. '/home/admin' doesn't exist and it's no longer referenced in the '/etc/passwd' file so the username cannot be determined. For me the fix was to change the '/home/admin' in the above line to something else that grep can match on to determine the user that resilio should run as. If you wonder what the user should be then have a look at the user that owns the start.sh script.
This is slightly brittle. It would be nice if it was more configurable without editing the scripts.